Design of a Three‐Helix Bundle Capable of Binding Heavy Metals in a Triscysteine Environment

A dream becomes reality: Until now, the engineering of novel metal-binding sites into a three-helix bundle has been an unrealized dream. By using an existing three-helix bundle as a template, a 3-Cys metal-binding site was generated at the C-terminal end by rational design to yield a well-folded and stable construct that encapsulates the heavy metals HgII, CdII, and PbII with high affinity and predefined coordination geometry (see picture).